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Java > Open Source Codes > org > jvyamlb > util > Base64Coder


1 /***** BEGIN LICENSE BLOCK *****
2  * Version: CPL 1.0/GPL 2.0/LGPL 2.1
3  *
4  * The contents of this file are subject to the Common Public
5  * License Version 1.0 (the "License"); you may not use this file
6  * except in compliance with the License. You may obtain a copy of
7  * the License at http://www.eclipse.org/legal/cpl-v10.html
8  *
9  * Software distributed under the License is distributed on an "AS
10  * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
11  * implied. See the License for the specific language governing
12  * rights and limitations under the License.
13  *
14  * Copyright (C) 2007 Ola Bini <ola@ologix.com>
15  *
16  * Alternatively, the contents of this file may be used under the terms of
17  * either of the GNU General Public License Version 2 or later (the "GPL"),
18  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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25  * the provisions above, a recipient may use your version of this file under
26  * the terms of any one of the CPL, the GPL or the LGPL.
27  ***** END LICENSE BLOCK *****/
28 package org.jvyamlb.util;
29
30 /**
31  * @author <a HREF="mailto:ola.bini@ki.se">Ola Bini</a>
32  */
33 public class Base64Coder {
34     // Mapping table from 6-bit nibbles to Base64 characters.
35 private final static char[] map1 = new char[64];
36     static {
37         int i=0;
38         for(char c='A'; c<='Z'; c++) map1[i++] = c;
39         for(char c='a'; c<='z'; c++) map1[i++] = c;
40         for(char c='0'; c<='9'; c++) map1[i++] = c;
41         map1[i++] = '+'; map1[i++] = '/';
42     }
43     
44     // Mapping table from Base64 characters to 6-bit nibbles.
45 private final static byte[] map2 = new byte[128];
46     static {
47         for(int i=0; i<map2.length; i++) map2[i] = -1;
48         for(int i=0; i<64; i++) map2[map1[i]] = (byte)i;
49     }
50     
51     /**
52      * Encodes a string into Base64 format.
53      * No blanks or line breaks are inserted.
54      * @param s a String to be encoded.
55      * @return A String with the Base64 encoded data.
56      */
57     public static String JavaDoc encode(final String JavaDoc s) {
58         return new String JavaDoc(encode(s.getBytes()));
59     }
60
61     /**
62      * Encodes a byte array into Base64 format.
63      * No blanks or line breaks are inserted.
64      * @param in an array containing the data bytes to be encoded.
65      * @return A character array with the Base64 encoded data.
66      */
67     public static char[] encode(final byte[] in) {
68         int iLen = in.length;
69         int oDataLen = (iLen*4+2)/3; // output length without padding
70 int oLen = ((iLen+2)/3)*4; // output length including padding
71 char[] out = new char[oLen];
72         int ip = 0;
73         int op = 0;
74         while (ip < iLen) {
75             int i0 = in[ip++] & 0xff;
76             int i1 = ip < iLen ? in[ip++] & 0xff : 0;
77             int i2 = ip < iLen ? in[ip++] & 0xff : 0;
78             int o0 = i0 >>> 2;
79             int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
80             int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
81             int o3 = i2 & 0x3F;
82             out[op++] = map1[o0];
83             out[op++] = map1[o1];
84             out[op] = op < oDataLen ? map1[o2] : '='; op++;
85             out[op] = op < oDataLen ? map1[o3] : '='; op++; }
86         return out;
87     }
88
89     /**
90      * Decodes Base64 data.
91      * No blanks or line breaks are allowed within the Base64 encoded data.
92      * @param in a character array containing the Base64 encoded data.
93      * @return An array containing the decoded data bytes.
94      * @throws IllegalArgumentException if the input is not valid Base64 encoded data.
95      */
96     public static byte[] decode(final byte[] in) {
97         int iLen = in.length;
98         if (iLen%4 != 0) throw new IllegalArgumentException JavaDoc ("Length of Base64 encoded input string is not a multiple of 4.");
99         while (iLen > 0 && in[iLen-1] == '=') iLen--;
100         int oLen = (iLen*3) / 4;
101         byte[] out = new byte[oLen];
102         int ip = 0;
103         int op = 0;
104         while (ip < iLen) {
105             int i0 = in[ip++];
106             int i1 = in[ip++];
107             int i2 = ip < iLen ? in[ip++] : 'A';
108             int i3 = ip < iLen ? in[ip++] : 'A';
109             if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
110                 throw new IllegalArgumentException JavaDoc ("Illegal character in Base64 encoded data.");
111             int b0 = map2[i0];
112             int b1 = map2[i1];
113             int b2 = map2[i2];
114             int b3 = map2[i3];
115             if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
116                 throw new IllegalArgumentException JavaDoc ("Illegal character in Base64 encoded data.");
117             int o0 = ( b0 <<2) | (b1>>>4);
118             int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
119             int o2 = ((b2 & 3)<<6) | b3;
120             out[op++] = (byte)o0;
121             if (op<oLen) out[op++] = (byte)o1;
122             if (op<oLen) out[op++] = (byte)o2; }
123         return out;
124     }
125 }
126
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